Method and apparatus for etching



Dec. 2l, 1965 R, C, BENTON ETAL 3,224,914

METHOD AND APPARATUS FOR ETGHING Filed Feb. 19, 1964 4 Sheets-Sheet 1 INVENTORS ROBERT C. BENTUN GUNTER DECKER ATTORNEY Dec. 21, 1965 R. c. BENTON ETAL 3,224,914

METHOD AND APPARATUS FOR ETCHING Filed Feb. 19, 1964 4 Sheets-Sheet 2 FIG.2

Dec. 21, 1965 R. c. BENTON ETAL 3,224,914

METHOD AND APPARATUS FOR ETCHING 4 Sheets-Sheet 3 Filed Feb. 19, 1964 INVENTORS ROBERT C. BENTON BY@ www ATTORNEY Dec. 21, 1965 R. c. BENTON ETAL 3,224,914

METHOD AND APPARATUS FOR ETCHING Filed Feb. 19. 1964 4 Sheets-Sheet 4 FIG] L, L2 FIG.5

' N. c. 21,8 OPENS WHEN 2/40 TIMER BAFFLES OPEN 222 202 ---o ocT ECT f 230 SCT 232 2 254` @2 4 226 33 FCT L] 7L o OPENS WHEN 228 204 BAE/:LES CLOSE BAFFLES INVENTORS ROBERT C. BENTON UNTER DECKER BY o ATTORNEY United States Patent Office 3,224,914 Patented Dec. 2l, 1965 3,224,914 METHOD AND APPARATUS FR ETCHING Robert C. Benton, State College, Pa., and Gunter Decker, Solingen, Germany, assignors to Chemcut Corporation, a corporation of Pennsylvania Filed lieb. 19, 1%4, Ser. No. 346,011 13 Claims. (Cl. 156-2) The present invention relates to a method and apparatus for etching surfaces which have been provided in selected areas with an etch resist coating; in industrial etching and in the photoengraving phase of graphic arts etching, the selected area which is retained is the so-called image area of a metal surface. This invention is primarily adapted for etching with multiphase etchants which are liquid, sidewall-protection type emulsions.

In the specific field of graphic arts etching, a printing plate or photoengraving plate of magnesium, zinc, copper, aluminum, or appropriate alloy having a surface to be etched, is generally secured to the underside of the lid of an etching tank in a face down position above the level of etching liquid stored therein. Within the tank charnber, beneath the plate7 power operated iiuid forcing means serves to impinge the fluid in a paddlesplashed spray or pressure-induced spray against the face of the plate. Inasmuch as it is desired to direct the spray uniformly over the face being etched, an intricate and relatively heavy mechanism is sometimes provided in the tank lid to give the plate a rotational movement with respect to the liquid being impinged against it. As etching proceeds, cavities form in the face of the plate in all non image areas because they are unprotected by the resist coating.

lf a multiphase etching liquid is employed, a protective etch resistant film builds up on the sidewalls or shoulders of those cavities as they are formed. The protective film prevents unwanted undercutting of the image areas which can be caused due to the continuous action of the etching liquid. Multiphase etchants usually contain, along with an aqueous phase, a few percent by weight of an organic, non-aqueous phase such as a petroleum solvent, or some petroleum hydrocarbon derivative, or a petroleum hydrocarbon, broadly. The aqueous phase consists of water, a surface active agent in amount of the order of two percent by weight or less, and the balance being an active etching agent such as nitric acid, ferrie chloride, or other suitable corrosive agent depending upon the selected elemental metal or alloy to be etched.

In theory, when an impinged emulsion has a uniform high force for providing the proper Velocity and after this force has already agitated and emulsitied the phases thereof into intimate dispersion with one another, the organic liquid phase will form a film on the face of the plate to be treated. Due to the liquid velocity, however, this film is broken and the aqueous phase penetrates the film on the surfaces normal to the direction in which the etching bath is thrown. The sidewall surfaces are parallel to the path of impingement. There is insufficient lateral force to cause the aqueous phase to penetrate the organic film on the sidewalls and the sidewall surface areas of the plate are not etched.

It has been found that the uniformity with which this protective tilm builds up on the cavity sides is determined by the effective ilow of the impinged liquid. When an etchant liquid spray is directed without careful control,

it tends to build up a non uniform protective film on the sides of the cavities and results in etched plates of unsatisfactory quality.

Improper procedure in controlling the effective flow accounts for many, if not most, of the difficulties of prior etching techniques. Startup is found to be particularly critical in the procedure. Difficulties are created preliminary to the actual etching when the pre-emulsiiication of etchant by agitation beforehand is insufficient or lacking altogether, or when the etchant temperature is not stabilized beforehand, or when the impingement velocity is not stabilized beforehand. Further dilificulties have been found to arise when the fluid impingement is intermittent, or when the impingement follows a repetitions pattern, or when impingement velocity is allowed to fall off or vary when the etching is in process or is being terminated.

It is an object of the present invention to obviate the foregoing difficulties and to provide an etching process and etching means capable of producing a more uniform protective film upon the sides of the cavities formed in an etched metal surface.

The relative rotation of the plate and liquid flow is achieved herein through compound motion of the impinging means in a random in and out movement combined with revolving movement. In one embodiment of the invention, the plate is above the impinging means and is held stationary or relatively so. In this way, the lid of the tank is unweighted with the intricate mechanism of prior devices used to provide rotational movement to the plate, and hence a simplified operating procedure results.

More particularly, We provide according to the invention, pressure induced spray means comprising a frame of spray nozzles, and mounting means driving connected to the nozzle frame for horizontally orbiting the nozzles through a cycloidal evolution pattern which .is non-repetitive in any two successive orbits, the mounting means comprising a swinging head, a frameeconnected post carried on an eccentric portion of the head so as to mount the frame to turn thereon, and a second post defining an axis and supporting the swinging head whereby the frame of nozzles revolves or orbits about that axis as the frame turns.

This invention also provides, for use with a plate holder and an oscillating spray nozzle frame which are mounted in spaced apart relation: shiftable baflies in that space having an undisplaced position in which they are operatively interposed across the spray path; a motor connected to displace the battles in opening movement for unblocking the plate and having a bathe-closing control switch connected to the motor for causing it to close the baffles; and timing means, the timing means being operable following baille opening movement to time an etching period and thereupon automatically, through actuation of the control switch, causing the motor to close the bales across the spray path for terminating etching.

Our apparatus, as just described, therefore provides a multiphase-etchant, object-spraying process including the novel steps of preagitating the etchant, by discharge in pressure induced sprays against baiiles having an interposed position blocking the object, thereby emulsifying the phases into intimate dispersion with 'one another; unblocking the object by movement of the baiiles to a displaced position, for spray etching the object; timing the period for etching; and restoring the baffles at the end of the timed period into interposed relation to the sprays for reblocking the object and terminating etching without terminating the agitation.

The present method and apparatus are primarily adapted for etching in the graphic arts field wherein the object or a set of the objects is introduced into the machine, the machine is operated for etching through a complete cycle and then is stopped, and the etched objects are emptied to clear the machine for the next cycle. Within the broader aspects of the invention, eg., in the industrial field, the cycloidal nozzle moving mechanisrn is equally well adapted for continuous etching wherein a continually running conveyor conveys a succession of objects through the machine. These objects enter therein from one side and leave from the other, after having been subjected in transit to oscillating spray from the moving nozzles which are `located above and/ or below the conveyor.

Other features, objects and advantages will either be specifically pointed out or become apparent when, for a better understanding of the invention, reference is made to the following written description, taken in conjunction with the accompanying drawings which illustrate a preferred embodiment of the invention and in which:

FIGURE l is a left side elevational view of the spray etching machine, taken along the section lines I--I of FIGURE 3;

FIGURE 2 is a top plan view;

FIGURE 3 is a front elevational view;

FIGURE 4 is a right side elevational View;

FIGURE 5 is a schematic diagram of an electric circuit for controlling spray-blocking bafiies in the machine;

FIGURE 6 is an explanatory sketch of the particular cycloidal motion which is imparted to the spray nozzles; and

FIGURE 7 is a side elevational view of a modification of the invention.

More particularly in reference to the drawings, an etching machine is illustrated having a generally boxshaped tank chamber or spray chamber 1t) and a side chamber 12. The box of the machine is made fluid tight at the joints and is covered by a lid 14 carrying a handle 16 and pivoted centrally to the top of the spray chamber by means of a hinge 18.

The spray chamber 10 contains, as the principal components, a shield and holder assembly 20, a spray nozzle frame 22 arranged to oscillate in spaced apart confronting relation below the shield and holder assembly, a planetary mechanism generally indicated at 24 supporting the frame 22 in its aforesaid relation with respect to the shield and holder assembly, and a tank 26 which holds etchant and which is located in the lower portion of the chamber l0 along the rear wall. The side chamber 12 carries a control box 28 at the front of the machine and contains within the side chamber 12 an etchant pump system 30, a drive motor 32 which is connected to the planetary mechanism 24 for oscillating the spray nozzle frame, and a shield motor 33.

The tank 26 has a sealed bottom wall 34 disposed between a vertical rear chamber wall 36 and a short intermediate vertical wall 38 at the front of the tank. The wall 38 is joined by a forwardly and diagonally upwardly tilted drain pan 40 which is connected to a vertically extending front wall 42 of the spray chamber 10. A mounting base 44 is secured to the pan 40 and carries thereon a lower post 46 of the planetary mechanism 24. A vertically aligned pedestal 48 which is below and which supports the base 44 is supported upon a machine fioor 50.

The lower post 46, which is hollow, is a fixed member of the planetary mechanism and rotatably carries on its reduced diameter, upper end an eccentric or head consisting of an upper plate 52, a lower plate 54, and a hollow enclosure 56 which is bolted between the plates. The head, which is circular shaped, is mounted to swing horizontally about a fixed central axis of revolution 58 defined by the lower post 46. A driven worm gear 6) of the planetary mechanism is secured to the bottom of the head and drives the head. The gear 60 is rotatably supported on a shoulder of the lower post 46, which acts a thrust bearing.

An upper post 62 is mounted to turn on the swinging outer end of the eccentric or head, and similarly to the lower post 46, is of hollow construction. The two posts stand vertically and are provided with rows of respective fluid ports 64 and 66 so that they communicate freely with one another within the enclosure 56. Suitable seals (not shown) between the head and the posts 46 and 62 and suitable gaskets (not shown) between enclosure 56 and the plates 52 and 54 prevent leakage in the head.

A planetary pinion 68 which is fast to the bottom of the upper post 62 meshes with a fixed sun gear 70 (FIGURE l) which is secured to the lower post 46. The pinion 68 has fewer teeth than the fixed gear 70. As a result, the post 62 turns on its axis at nearly twice the rate at which it orbits, but in the same direction as it orbits about the axis of revolution 58, which axis passes concentrically through the post 46 and the sun gear 70.

The spray nozzle frame 22 is in communication with and is afiixed to the upper end of the upper post 62, there being a collar 72 carried by the frame and engaging a thrust washer (not shown) on the upper plate 52 of the head. The collar 72 is afiixed to the lower portion of a frame T 74 which supports the main pipe of the nozzle frame 22. The frame has a central Vertical axis '76 which is concentric with the frame T 74 and with the upper post 62 (FIGURE l).

The spray nozzle frame 22 is horizontally disposed; the frame is of a generally circular shape and is defined by a longitudinally extending main pipe 78 joined by a series of transversely disposed side pipes 80. The side pipes 80 are arranged in order of decreasing lentgh as they approach the opposite ends of the pipe 79 and, adjacent their outer extremities, the longer pipes are joined together by longitudinally extending short tie pipes 82. The tie pipes 82 are not in communication with the rest of the frame, although the side pipes 80 are in fluid communication with and are supported by the main longitudinal pipe 78 which acts as a header. The side pipes 80 carry individual fixed nozzles generally indicated at 84 in FIGURE l, 2, and 3 and specifically identified by a superscript where necessary hereinafter. The number of nozzles ranges from a minimum of two spray nozzles located on the shortest side pipes to twelve nozzles provided on the lon-gest side pipes. The plural nozzles are arranged to have individual, vertically disposed axes, and collectively are seen (FIGURE 2) to be equally spaced apart orthogonally in a fore and aft relation alongside the longitudinal main pipe 78 and in side by side relation to one another in the direction of the side pipes 80. The etchant is delivered in a cone shaped spray from each nozzle so as to follow a vertical conical axis.

The shield and holder assembly 20 has fixed parts iirmly secured together comprising a pair of spaced apart upper guideways 86 (FIGURE 3) carrying narrow ledge strips 88, and a pair of lower guideways 96 carrying narrow ledge strips 92. An article holder comprising a pair of relatively adjustable transverse bars 94!v and 96 joined by longitudinally extending, spaced apart rods 98 is slideable on the ledge strips 88 between a centered, operative position indicated in solid lines in FIGURE l and a holder loading position generally indicated by the dotted lines 96a. The transverse bar 96 carries a pair of thumb screws 100 each engageable with one of the rods 98 in order to provide for adjustment of the frame dimensions of the holder, and each of the transverse bars 94 and 96 carries a set of spaced apart pins 102 on `which the actual etched articles such as photoengraving plates are supported. Each pin 102 has an upwardly extending tip portion on which the object rests in point contact.

The lower guideways 90 extend from the front to the rear of the machine between the vertical walls 36 and 42, and the ledge strips 92 carried thereby slideably support front and rear horizontally disposed spray shields or bales 104 and 106, respectively. A bridging strip 108 is carried at the adjacent edge of the rear bale 106 to overlaph the other baffle and prevent etchant from spraying upwardly between the two bales when they close together. A pair of power operated bafe shafts 110 and 112 is provided to open and close the baffles, each of the shafts 110 and 112, respectively, having a central rack pinion 114 which meshes with a longitudinally extending rack 116 carried by the corresponding one of the baffles 104 and 106. 'I'he shafts 110 and 112 rotate on fixed axes at respective front and rear points in the machine, being journalled for rotation in depending bearings 115 secured in xed locations to the assembly 20.

A fixed shield or baffle 117 is secured to the underside of the ledge strips 88 in a location at the front of the lid opening in the top of the machine. The battle 117 overlappingly complements the slidable front bathe 104 to prevent spray from reaching the operator when he opens the lid 14 (FIGURE l). The two baiiies 104 and 117 are in registry one below and one above the other when, as shown in FIGURE 4, the bafe 104 is displaced into its open position.

Means is provided for heating and cooling etchant in the tank 26. An electric heating element 118 is secured at its front end in an opening in the front wall 38 of the tank by means of a collar 120 sealed to that wall. The element 118 is supported in a frame 122 holding it in a horizontal position within the tank. For cooling purposes, an inlet pipe 124 in the side chamber 12 supplies water through an upper solenoid valve 126 and a lower solenoid valve 128 to one end of the header 130 of an upper set of pipes and to one end of the header 132 of a lower set of pipes. Water flows from one or both of the headers 130 and 132 through a portion of the sets of horizontal parallel pipes 134, transfers in end headers 136 into the remainder of the pipes 134, and is discharged fro-m the other end of the headers 130 and 132 (FIG- URES 2 and 3) into a water outlet pipe 138. An etchant waste pipe 140 is connected to a drain opening 142 in the tank bottom wall 34 and the pipe is drained by a drain valve 144 (FIGURES 2 and 5).

A centrifugal pump 146 included in the etchant pump system 30 is connected at its inlet with an L-shaped suction line 148 which communicates through an opening 150 in wall 38 of the etchant tank 26. The wall 38 extends between outer and inner side walls 149 and 151 of the spray chamber 10. The pump 146 is driven by a switch-controlled electric pump motor 152 of which the base is bolted to an inside wall 154 of the side chamber 12.

The centrifugal pump 146 has an overiiow discharge 156 which communicates through an opening 158 with the inner side wall 151 of the spray chamber 10. The pump 146 has a main discharge pipe `162 which delivers etchant fluid to an external filter 164 mounted to a base in the side chamber 12. Filtered etchant leaves the iilter 164 4through a radial line 168 leading to a central elbow 170 of the planetary mechanism 24. The line 168 contains a pipe union 172, a pressure gage fitting 174, and a valve 176. The valve 176 is controlled by a shaft 178 (FIGURE 2) leading to an external point where the shaft carries a valve handle 180. The valve 176 controls line pressure in the line 168. The operator sets this pressure and reads it from a line gage 179 which is connected by a tube 181 to the pressure gage fitting 174.

The elbow 170 is secured to the lower end of the hollow lower post 46 of the planetary mechanism 24. In this manner, etchant under controlled gage pressure is supplied from the pump 146 to the spray nozzle frame 22.

Within the side chamber 12, as seen in. FIGURE 4, the drive motor 32 for the planetary mechanism 24 is connected by two bevel gears (not shown) to a sprocket drive consisting of driving and driven sprockets 182 and a chain 184 trained thereover. A shaft 186 carries the driven one of the sprockets 182 and extends from the remote location of the electric motor 32 substantially radially inwardly to a point within the spray chamber 10 where it is journalled in a pair of bearings 188 (FIG- URE 2). A worm 190, disposed between the bearings 188, is fast to the shaft 186 and meshes with the worm gear 60 in a driving relation so as to oscillate the planetary mechanism 24. The base path of revolution is indicated by the dotted lines 187.

Within the side chamber 12, the shield motor 33 drives a sprocket 192 (FIGURE 4) which is connected by means of an endless chain 194 with a rst sprocket 196 which is fast to the baffle shaft and with a second sprocket 193 which is fast to the rear bafe shaft 112. The upper flight of the chain 194 engages the upper periphery of the rst sprocket 196 and the lower periphery of the second sprocket 198. As a result, the front and rear shafts 110 and 112 are positively rotated in opposite directions due to movement of the chain 194 in either direction, and the bales always move oppositely to one another.

The lower iiight of the chain 194 carries a protruding switch actuator 200 which moves between an open-bafe position shown in solid lines in FIGURE 4 and a dotted line position 200g taken when the bales 104 and 106 are fully closed. In the solid line position, the actuator 200 engages and opens a limit switch 202, and in the dotted line position 200a the actuator opens a limit switch 204, in each case deenergizing and stopping the baffle motor 33 through suitable actuator circuits, not shown.

A frame protective basin 206, including short vertical side walls joined uid tight to the machine floor 50, extends below the machine in laterally offset relation beyond the edges for collecting spillover or leakage of the etchant. A drain tting 208 (FIGURE 4) at the rear of the frame protective basin 206 is suitably connected to an outlet pipe (not shown). The machine oor 50 rests on a rectangular base frame made of supporting I-beams 209 and cross-connected angle and channel members.

The control box 28 at the front of the side chamber 12 includes a timer having a setting knob 210 (FIGURE 3) for moving a pointer 212 to a desired position on a timer dial marked off in time units. Suitable power switches generally indicated by numeral 214 are mounted on the console panel of the box, and circuit indicator light lenses are indicated by reference numeral 216.

The timer and associated motor actuator circuits are more clearly understood in the schematic diagram of FIGURE 5. The timer 218 receives electricity through service lines L1 and L2, of which the line L1 is connected to a terminal likewise indicated by the numeral L1 on the timer. The service line L2 is connected directly to a fourth contact terminal FCT on timer 218 and is connected through a hand-operated starting switch 214g to one contact terminal OCT which energizes the timer for a cycle of operation. A rst branch circuit 222 is connected between an eighth contact terminal ECT on the timer 218 and a rst phase winding 224 of the bathe motor 33. The limit switch 202 is included within the branch 222 and the limit switch 204 is included within another branch circuit 226. The branch circuit 226 is connected between a seventh contact terminal SCT on the timer and a second phase winding 228 of the motor 33.

A neutral wire 230 common to the rszt and second motor phase windings is grounded, and a red indicator lamp 216a is connected between the neutral wire 230 and the branch 222. A cross connection between the branches 222 and 226 adjacent their connections to the motor phase windings includes a capacitor 232 and a resistor 234 which are series connected to create a rotating magnetic field in the motor by providing a phase shift between the first and second phase windings.

When a timed cycle is desired, the operator manually closes the switch 214:1 which energizes the eighth contact terminal ECT and causes current to flow through the closed switch 202 and the branch 222 for a timed period, such as fifteen minutes. The baille motor 33 is set in rotation in one direction, which opens the bafiies so that the object is no longer shielded. The switch 202 automatically opens the circuit branch 222 at this point to stop the bafile motor. At the end of the timed cycle, the eighth contact terminal ECT of the branch 222 is deenergized and the timer causes current to fiow through the branch circuit 226 and the closed switch 204 so as to energize the windings 224 and 228 in proper phase relation to drive the motor 33 in an opposite direction. The motor 33 closes the bafiies and, when they are completely closed, the limit switch 204 is actuated, open-circuiting the branch 226 and stopping the motor 33.

The sketch of FIGURE 6 indicates the principle of cycloidal operation imparted to the nozzle frame of the machine. A large fixed inner circle 236 corresponds to the sun gear of the planetary system. The smaller rolling circle 238 corresponds to the planetary pinion and rolls about the periphery of the inner circle 236 in the direction of the arrow 240. The end portion 242 of an extended radius of the rolling circle 238 moves through a locus of points or path 244 having an in and out cornponent 246 relative to the fixed inner circle 236 and also an orbital component of which the radius R changes as the rolling circle 238 moves. On the next orbit, the in and out component 246 can be made to occur at some other position than the twelve oclock position shown in FIGURE 6, for example, a nine oclock position, a one oclock position, etc.

The motion of the end portion 242 of the extended radius has an evolution pattern generating a curtate epicycloid, or more technically an epitrochoid. By proper selection of the tooth ratio (or relative radii) between the circles, the forced path 244 does not repeat itself for a considerable number of orbits about the fixed circle 236. Inasmuch as most if not all of the nozzles of the present nozzle frame follow epitrochoid paths which are in varying degrees like the path 244, the nozzles execute a random motion in which their successive orbits are forced out of conformity with one another. Hence, an object being etched is confronted with a continually changing, enforced pattern of pressure induced sprays.

Following is one example of specifications for the present etcher:

Spray line pressure at gage fitting `174 2-10 p.s.i., preferably -7 p.s.i.

Nozzles in frame 22 92 nozzles.

Nozzle spacing, orthogonally 4 center to center.

Sun gear 70 40 teeth.

Planetary pinion 68 24 teeth.

Tooth ratio 5:3.

E-ccentricity (throw of planetary head 2 between axes SS and Material of etching machine Polyvinyl chloride plastic panels.

Timer 218 Eagle reset timer made by Eagle Signal Company.

Etchant emulsion Oil phase plus wetting agent plus acidic agent plus balance water.

8 In the machine of the example just given, one nozzle individually identified by reference numeral 84 may be noted for an understanding of the points reached in the course of five orbits. The successive positions along the trace of the epitrochoid are identified in the following table, reference being to FIGURE 2 of the drawings.

Position: Orbital angularity 84 0 (no orbits completed). 84a 135.

Mb 270. S40 360 (first full orbit). 84d 720 (second full orbit).

84 1080 (third full orbit). 84C' l440 (fourth full orbit). S40. l800 (fifth full Orbit).

In operation of the present machine, the lid 14 is opened whereupon the operator adjusts the holder by shifting the transverse bar 96 relative to the two rods 98 to set the proper dimensions for the holder frame. The object to be etched, such as a photoengraving plate, is laid face down in the holder. The holder is advanced into the solid line, operating position shown in FIGURE l and the lid 14 is closed.

The operator then operates the appropriate switches 214 to accomplish the following: the electric pump motor 152 is set in operation to initiate operation of the etchant pump system, the electric drive motor 32 is set in operation to initiate operation of the planetary mechanism 24, and the electric heating element 118 is energized to warm the etchant in the tank 26.

After delay of a few minutes suitable to intimately mix the phases of a multiphase etchant which is preferable used as the solution in the tank of the machine, and after the etchant is warmed and the temperature is properly stabilized, the timer 218 (FIGURE 5) is adjusted to the time setting desired by means of the knob 21) (FIGURE 3) whereupon the starting switch 214a (FIGURE 5) is closed to run the machine through an automatic time cycle. The timer, causing the red indicator lamp 2160i to light, also energizes the baille motor 33 which opens the baffles and which is automatically de-energized by the limit switch 202. The object is sprayed by nozzles 84 moving as described.

The timer 21S times out so as to `deenergize the red indicator lamp 216:1 and operate the motor 33 in the opposite direction. The baffles are closed by the sprocket chain, thereupon de-energizing the baille motor. The operator then opens the lid 14 (FIGURE 4), slides the holder into the solid line, loading and unloading position, and removes the etched object for rinsing and the necessary further steps followed in graphic arts, resistcoated etching procedure.

The process is then repeated.

It will be understood that the planetary mechanism and etchant pump system are continuously operated during a succession of etching cycles of the machines. Uniform temperature distribution is thus maintained and, more importantly, the phases of the etchant are kept agitated as a finely divided dispersion within the emulsion. The agitation is due to the pump rotation and due to forcing the spray under pressure from the nozzles, but mainly due to the high speed impingement of fluid continually against either the closed baffles or theactual objects and surrounding surfaces inside the machine. No paddles, circulatory stirring in the tank, or conventional agitation is necessary to keep the etchant emulsified. It will be further understood that the etchant gage pressure is in a small, closely controlled range at all times for uniformity. Also the temperature of the etchant is held in a closely controlled narrow range by means of the heating element or by means of water flow through the cooling pipes 124 and 138. The heating element is usually not employed after initial warm-up because chemical etching of metal is essentially an exothermic reaction.

Depending upon the metal being etched and the corrosive chemicals in the etchant liquid, the cooling water will be used in varying amounts and in some applications is continually circulated after Warm-up conditions are established.

In FIGURE 7, a continuous spray etcher 24 is shown having an upper planetary mechanism 24a and a lower planetary mechanism 24h. Objects 248 to be etched are loaded on a continuously driven conveyor 250 so as to be conducted through the spray chamber 252 and through the balance of the machine (not shown). An upper nozzle frame 22a which directs down-sprays is caused to oscillate in a horizontal plane by the upper planetary mechanism, and a lower nozzle frame 22b which directs up-sprays is similarly caused to oscillate by the lower planetary mechanism. The conveyor includes synchronously rotating rollers 254 arranged with sufficient orthogonal spacing therebetween so that the upsprays reach the undersides of the objects 248 with about the same etching effectiveness as the upper sides of the objects are affected by down-sprays from the nozzle frame 22a thereabove.

A vertically extending shaft which is motor driven and which is indicated by the dotted line 256 is connected by suitable bevel gears, not shown, to drive the planetary mechanisms 24a and 24h at the same speed and in the same or in a symmetrically opposite phase relationship to one another. It is not necessary that the frames orbit in the same direction about the vertical center line of the spray chamber 252. Further details of a continuous etching structure and method are disclosed and claimed in my U.S. Patent No. 3,082,774, which disclosure being hereby completely incorporated by reference.

As herein illustrated, the invention is shown embodied in machines wherein the spray is directed at right angles to the plane of the nozzle frame and in the vertical direction up or down. lt is evident that the nozzle axes can be fixed at a slight angle away from normal to the plane of the frame and that, irrespective of the nozzle angle, the frame will be oscillated in its own plane which will be arranged essentially parallel to the main surface of the work. If for example the work is to be etched while in a vertical position in the machine, the plane of the frame and its plane of oscillation will be vertical. In both embodiments illustrated, we have avoided etcher designs of the type which has hitherto employed a tank lid having mechanism secured thereto, e.g., heavy mechanism for mounting and rotating the plate. Loading and unloading of the objects in the present machines are readily accomplishe-d; an unweighted lid is used and the nozzle mechanism itself performs the requisite oscillatory motion. lt is important in achieving the enhanced results hereof that the spray emulsification, the spray velocity, and the spray temperature are all stabilized at optimum value prior to exposing the objects to the spray.

Variations Within the spirit and scope of the invention described are equally comprehended by the foregoing `description,

What is claimed is:

l. In an etching machine:

a horizontal holder for objects;

plural spray nozzles vertically spaced apart from the holder and transversely spaced orthogonally from one another in fore and aft relation and in side by side relation; and

single means supporting said plural nozzles for movement in a plane parallel to said horizontal holder, including a frame common to all nozzles fixing them in the relation aforesaid, and planetary mechanism having an eccentric head portion which is drivingly connected to the frame and which when rotated swings said frame with a cycloidal motion, whereby the individual nozzles after swinging through each full-orbit of a cycloidal path swing through a non- `repetitive path with respect thereto on the next orbit;

said single means being hollow, and defining a fluid conduit for connection to a fiuid supply for supplying fluid to said nozzles continuously in all positions of swing of said plural nozzles;

said head portion having a gear therefor made fast thereto, remote motor means, and a toothed positive drive interconnecting the remote motor means and the gear for said head portion.

2. In an etching machine:

a horizontal frame of spray nozzles, each having a vertical axis and a fixed spray angle;

single means supporting said frame for cycloidal motion and including a rotatable eccentric head portion mounting the spray nozzles so that when the head portion rotates, the nozzles turn and revolve, respectively, about a rotational axis constituting the central axis of said frame and about a separate axis parallel to the first;

a gear for the head portion and made fast thereto;

remote motor means;

means including gearing and a shaft interconnecting the gear for the head portion and the remote motor means to provide a positive toothed drive for the nozzle frame; and

supporting means, on which the objects to be sprayed are disposed, mounted at a different vertical level in said machine from said frame and exposed to the spray pattern from said nozzles.

3. ln a machine for etching objects:

a horizontal frame of spray nozzles, each having a fixed spray angle;

single means supporting said frame to oscillate the spray nozzles in a horizontal plane;

second means for supporting the objects thereon and mounted at a vertically spaced apart level in said machine from the nozzles; and

fixed and movable bafiie means having a cooperative arrangement to effectively `block the nozzles and obviate all spray from reaching the supported objects on the second means.

`4.. An etching machine having first means for shiftably mounting objects to be spray etched;

a horizontal frame of spray nozzles, each having a fixed spray angle;

single means supporting said frame to oscillate the nozzles in a horizontal plane which is spaced apart at a different vertical level in said machine from the first means so as to expose objects thereon to the spray pattern from said nozzles; and

fixed and movable baffle means in the space between said first means and said nozzles, said movable means comprising block-oft baffles movable into a position blocking the entire spray pattern of said nozzles; said fixed baffle means having an offset position for blocking random spray from said nozzles; said first means being shiftable from an offset position in the shadow of said fixed baffle means into a position above the movable baffles so that movement of said baffles from the pattern of the spray nozzles exposes the objects shiftably mounted in the first means to spray etching.

5. An article etching machine comprising:

a frame ot' etchant spray means;

supporting means drivingly connected to said frame to move said spray means in a pattern of evolution establishing an oscillating spray path;

second means on which the articles are disposed effective to expose articles in the spray path of and in spaced apart relation to the etchant spray means; and

baffle means in `the space between said spray means and the articles having a position of placement blocking the articles from said spray path and movable into a displaced position unblocking the articles for exposure to etching.

6. In a machine providing an article holder for use in etching articles: the combination of a suppor-ted frame with fixed etchant spray means theresupporting means in fluid communication with said frame for supplying etchant liuid to the spray means to establish a path of spray;

mounting means for shiftably mounting the holder so as to expose said articles in vertically spaced apart, mutually confronting relation to the etchant spray means;

baille means shiftable in the space between said spray means and articles; and

power means connected to shift said balie means between a displaced position affording a period of etching and a position entirely blocking the articles from the path of spray.

7. 1n an etching machine having first means which carries the article to be etched, the combination comprising:

supported means for impinging etchant in a spray path against the articles;

supporting means in fluid communication with the etchant impinging means for supplying etchant fluid thereto to establish a path of spray;

baffle means fixed in said machine in an offset relation to the etchant impinging means;

mounting means for mounting the first means in a disposition with the articles in the spray path of and in vertically spaced apart relation to the etchant impinging means; and

baffle means mounted to shift between an undisplaced,

spray blocking position in said space in registry with the etchant impinging means and the articles, and a displaced position at least partially in registry with the fixed baffle means.

8. The invention of claim 7, wherein said mounting means is arranged for shiftably mounting said first means for movement between its disposition aforesaid and a disposition of registry behind the fixed baie means.

9. In an etching machine having fluid impinging means developing a spray path, the combination of:

a holder for articles;

mounting means to support said holder in spaced apart relation to and in the spray path of the fluid impinging means;

shiftable baffle means in said space having an undisplaced position in which the baffle means is operatively interposed in the spray path;

energizable means operable to shift said bathe means between said undisplaced operative position and a displaced position affording a period of etching of an article; and

means effective to control the energy to operate said energizable means and connected to respond to movement of the baffle means into the positions aforesaid to deenergize said energizable means.

10. In an etching machine having fluid impinging means developing a spray path, the combination comprising:

a holder for articles;

sliding plates confronting the holder having an open displaced position and a closed position contacting one another to block the spray path;

energizable means drivingly connected to the sliding plates including a power element in common thereto to operate the plates in relatively opposite directions for opening and closing the plates;

actuator -means adapted to be contacted by the power elem-ent when said element slides the plates into their positions aforesaid; and

means responsive to said contact to deenergize said energizable means.

11. In a machine for etching articles having motive means for impinging thereagainst etching liuid in a path, the combination of:

movable, block-off baffles having a closed position blocking said articles entirely from the path of irnpinging fluid;

motor means connected to displace said baffles in opening movement for unblocking the articles and having a bathe-closing control switch actuable for causing said motor means to close the baiies; and

timing means; said timing means operable following said opening movement to time an etching period and thereupon automatically actuate said switch to cause the motor means to close said batiies for terminating etching.

12. Process of etching objects by spraying with a multiphase etchant, comprising the steps of:

pre-agitating the etchant in pressure induced sprays,

against baffles in an interposed position blocking the objects, for breaking up and emulsifying the phases into intimate dispersion with one another; unblocking the objects by movement of the baffles to a displaced position, for spray etching the objects; timing the period for etching; and

restoring the baffles at the end of said timed period into interposed relation to the sprays for re-blocking the objects, terminating etching, and, all at the same time, sustaining the emulsified condition by continuing to agitate and break up the etchant phases.

13. Apparatus for etching fixed objects by means of pressure induced spraying with a multiphase etchant, wherein the sprays operate continuously, comprising:

movable baies initially having an interposed relation to the sprays, both blocking the objects and emulsifying the etchant due to its impingement thereon so as to agitate and break up the etchant phases; control means for moving and stopping the baflies in a displaced position, unblocking the objects so that the spraying means spray etch them for a timed period; and control means effective to restore the baflies, at the end of said timed period, into their interposed relation for re-blocking the objects, terminating etching and, all at the same time, sustaining the emulsiiied condition by continuing to agitate and break up the etchant phases.

References Cited by the Examiner UNITED STATES PATENTS 1,373,658 4/1921 Freer 156-14 1,888,542 11/1932 Rosberg. 2,261,988 11/1941 Gaebel 134-194 2,275,189 3/1942 Wieghart 134-176 X 2,279,619 4/1942 Fisher 134-179 X 2,293,201 8/1942 Gaebel 134-58 2,351,342 6/1944 Karlstrom. 2,360,676 10/1944 Henderson et al. 156-14 X 2,392,540 1/1946 Lyman 134-180 X 2,960,991 11/1960 Bland 134-194X 3,106,217 10/1963 Henderson 134-58 3,136,671 6/1964 Martz et al 156-14 CHARLES A. WILLMUTH, Primary Examiner.

GEORGE J. NORTH, Examiner.

ROBERT L. BLEUTGE, Assistant Examiner. 

12. PROCESS OF ETCHING OBJECTS BY SPRAYING WITH A MULTIPHASE ETCHANT, COMPRISING THE STEPS OF: PRE-AGITATING THE ETCHANT IN PRESSURE INDUCED SPRAYS, AGAINST BAFFLES IN AN INTERPOSED POSITION BLOCKING THE OBJECTS, FOR BREAKING UP AND EMULSIFYING THE PHASES INTO INTIMATE DISPERSION WITH ONE ANOTHER; UNBLOCKING THE OBJECTS BY MOVEMENT OF THE BAFFLES TO A DISPLACED POSITION, FOR SPRAY ETCHING THE OBJECTS; TIMING THE PERIOD FOR ETCHING; AND RESTORING THE BAFFLES AT THE END OF SAID TIMED PERIOD INTO INTERPOSED RELATION TO THE SPRAYS FOR RE-BLOCKING THE OBJECTS, TERMINATING ETCHING, AND, ALL AT THE SAME TIME, SUSTAINING THE EMULSIFIED CONDITION BY CONTINUING TO AGITATE AND BREAK UP THE ETCHANT PHASES. 